Persistent non-familial asymptomatic hyperphosphatasemia: a report on three cases.

Three male children, aged 9 days, 2 years and 13 years, were found to have elevated serum alkaline phosphatase (ALP) activity (hyperphosphatasemia) in the absence of disease. In these three cases, elevation of ALP activity had persisted for 6-10 years. These patients did not inherit the disease from their parents. Isoenzyme determination revealed a skeletal origin of the elevated ALP in the three patients. They were diagnosed as having persistent non-familial asymptomatic hyperphosphatasemia (PNAH) which differs from transient and persistent asymptomatic familial hyperphosphatasemia. Reviewing the literature, although the term PNAH had not been used, two similar cases have been reported in a 24-year-old female and in a 27-year-old female. PNAH may be another type of benign hyperphosphatasemia.